Inorganic gel composition



Patented Jan. 16, 1934 UNITED STATES ATENT INORGANIC GEL COMPOSITION RoyCross, Kansas City, Mo., assignor to Silica Products (30., Kansas City,Mo., a corporation of Delaware N Drawing. Application March 28, 1929Serial No. 350,823

7 Claims.

' and covers more specific features relative to the production and useof plastic inorganic materials and emulsions. I

It relates particularly to the behavior of natural and artificialhydrous silicates of alumina which have the property of normal swellingto a greater or lesser degree in the presence of water. Naturalsilicates of this type have been found which are capable of forming afairly stifif gel with from two to twenty parts of water though theproduct of the best commercial deposits representing the averagematerial is practically never found which will form a gel when more thanten parts of water are used. However, when these inorganic swellingclays or hydrous silicates are mixed with a small amount of an alkaliearth silicate-it has the property of forming a gel in many cases withfive times as much water as is the case before the alkali earth silicateis added. An alkali silicate improves the jelling properties but thegreatest effect seems to be obtained from alkali earth silicates; alsosimilar improvement is obtained by the action of alkaline substances ofany kind such as lime (calcium oxide or hydroxide), alkali phosphate,carbonate, etc.

While, as stated above, alkaline substances such as lime are effectivein getting exactly the right results, they must be used in such amountand with such amount of water as to give the right hydroxyl ionconcentration or hydrogen ion concentration. It is very important tohave this reaction or hydrogen ion concentration kept within fairlynarrow limits to get the maximum gel effect. In the case of lime, thishydrogen ion concentration will vary with the amount of lime and due tothe dilution effect. Too much lime or too far on the alkaline sidediminishes the strength of the gel. For this reason, alkaline earthsilicates or Portland cement have been satisfactory; But even here, inthe case of Portland cement containing large excess of free lime, toomuch alkalinity may result; whereas in some cases the alkalinity mightbe insufiicient. For this reason, in certain cases where economicconditions will permit, alkaline substances of exactly the righthydrogen ion concentration may be advantageously used. One of thesesubstances is magnesium oxide. Being practically a pure substance andgiving practically the same hydrogen ion concentrations regardless ofdilution, it has been found very useful. In some localities, of course,the cost is excessive. In such cases it is desirable to use burneddolomite or calcined magnesite.

For this purpose the dolomite or magnesite should be burned to atemperature that will effect decomposition of the magnesium carbonate tomagnesium oxide, but will not effect any appreciable decomposition ofthe calcium carbonate to calcium oxide. The burning of dolomite attemperatures between 250 C. and 825 C. has therefore been effective inproducing a material that, when added in any proportions to bentonite,will give the maximum gelling effect. From 0.5% to 10% of calcineddolomite or magnesite has proved useful for various purposes inimproving the gel value or plasticity. The advantage of using alkalinesubstances having the same hydrogen ion concentration as given by amixture of magnesium oxide and water is the fact that the bentonitemaintains to a large degree its reversibility. The hydrating action orthe avidity of Portland cement for water tends to diminish thereversibility. In some cases, of course, as herein stated, thisreversibility is not desired. In other cases, it is desired to thefullest degree.

Typical commercial alkali earth silicates include any type of Portlandcement, some types of natural cement, blast furnace slag andcombinations of lime and sodium silicate. The most desirable gelstrengthener on account of its other properties, its commercialavailability and cheapness, is ordinary Portland cement. The amount ofPortland cement required is dependent upon the stiffness of the geldesired. Much improvement in the jelling properties is obtained with aslittle as five per cent of Portland cement based upon the hydroussilicate of alumina used. A desirable quantity is about twenty per centfor many purposes. In those cases in which the property of the cemententers into the composition, any amount of cement may be used. In manycases, a mixture of equal parts of cement and the swelling clayissatisfactory.

Other substances affecting the gel value of bentonite within the scopeof this invention include magnesium borate basic carbonate, fluoride,phosphate, bismuth salts and most metal borates, phosphates, fluoridesand subcarbonates.

One of the important features of this invention is dependent upon thefact that when this alkali earth silicate of alumina such as Portlandcement is used in conjunction with the swelling clay, the reversibilityof the swelling action is overcome. For example, if ordinary bentonite,which swells upon the addition of water, is dried and water again added,the bentonite will again swell. However, if Portland cement is added inthe proportion of twenty pounds of Portland cement to til) eight-ypounds of bentonite, the jelling power of the bentonite is increasedfrom two to ten fold. When this hydrated mixture is now dried and wateragain added to-it. it has almost completely lost its jelling power orits ability to take on water so that the combination may then be said tobe irreversible. This property makes this invention particularly usefulbecause of the increase in waterproofing properties by reason "of thedecreased ability to swell or take on water after having once swelledand dried. In the use of this invention. it is desirable to provide fora dried substance which can be transported without being previouslymixed with water. This dried substance then when ready for use iscapable of being mixed with water to form plastics or emulsions of theconsistency desired.

Among the uses to which this material may be put therefore are (1) themanufacture of cheap paints. For such purposes, a typical mix would beapproximately as follows: natural hydrated silicate, gelatinizing clayor bentonite such as is found near Death Valley, California. or in theBlack Hills District in Wyoming, may be used as the basic material.White Portland cement is intimately mixed with it. Heavy hydrocarbon oilor linseed oil may be added. When the material is ready to use, it isthoroughly mixed with water forming a'thick emulsion which may beapplied as a paint. A typical mix would be as follows:

Parts White gelatinizing clay 25 White Portland cement 25 White zincoxide 25 Heavy hydrocarbon oil or drying oil This material may be packedand stored indefinitely in containers and when ready to use is mixedwith a suflicient amount of water to give a workable consistency. In atypical instance, this would depend upon the character of the cement andupon the character of the gelatinizing clay. Five hundred parts of watermore or less, is added to give the proper working consistency and thisis then applied to the surface by means of a spray or brush. The actionof the white Portland cement which is preferably of the quicklyhardening variety is to increase the gelatinizing property of thegelatinizing clay. For example, in a typical instance, the addition offrom five per cent to one hundred per cent of Portland cement togelatinizing clay or bentonite approximately quadruples its gelatinizingpower. Furthermore, it has the property of making the gelatinizingaction of the clay irreversible so that after the water has formed thegel and the gel has dried out. it becomes much less susceptible to thefurther action of water. This also is accomplished to some degree bythehydration of the cement. For this reason. the quickly hardeningcement is desirable so that the water of combination fully reacts beforedrying is completely ef fected.

The composition may be made consisting of the gelatinizing clay and thecalcium silicate or cement alone, or it may be made of the gelatinizingclay, the cement and the oil. In the first case. the oil may be added orthe water for making the plastic may be added without the oil. In thesecond case, the water only need be added. In cases where the whitecolor is not necessary, gelatinizing clays that are not perfectly whitemay be used. Also ordinary Portland cement or blast furnace slag may beused and a dark colored oil or asphalt may be satisfactory in thosecases \vhcre dark or black coating is to be made. It is desirable thatall materials except the oil, be ground to a high degree of fineness asis cus tomary in paint manufacture.

(2) For surface waterproofing of all types of construction materialssuch as concrete, steel, pipe lines, gypsum plaster products, timber andthe like. A typical method would include the application of theemulsion, bentonite, Portland cement, asphalt and water for themanufacture of a coating on freshly laid concrete roads to preventevaporatio of moisture and to provide a surface which would protect theconcrete and prevent excessive wearing, particularly in its earlierperiods of hydration. A typical mixture for this purpose would be asfollows:

Lbs. Bentonite 25 Ordinary Portland cement 5 High penetration asphaltcement 25 Water250 to 500 lbs. depending upon the consistency desiredand the amount to be applied per square yard.

Approximately the same composition may be used for applying to roads ofall kinds, including clay roads, this material taking the place ofordinary road oil. It has the advantage over ordinary road oil in thatthe asphalt used may be of a harder character than ordinary, thethinning being accomplished with water instead of with light oil ornaphtha.

(3) In the manufacture of roofing compositions containing fibrousmaterial. This composition provides a very much more gelatinousinorganic material for making such emulsions than is possible by anyother known means. In such cases, just sufficient Portland cement orother silicates or aluminate is used to greatly increase thegelatinizing value of the natural hydrous silicate. When bentonite aloneis used for this purpose, ordinarily the hydration is reversible. Thatis, after having been treated with water and dried it will again take upwater. By the use of Portland cement in the composition, the bentonitewill hydrate but once, so that the product after drying becomesresistant to the action of water. By the use of a large amount offibrous material and a large amount of water, this composition forms abasic material for insulation and as roofing, serves not only asinsulation against heat but also for waterproofing. The same compositionmay be used for other insulating purposes as in refrigeration.

(4) This composition also may be used for mixing with mineral aggregatein the laying of cold asphalt pavement. In this case, only enoughPortland cement need be used to make the hydration of bentonite orgelatinizing clay irreversible. The composition of gelatinizing clay,Portland cement and asphalt may be made also to include mineralaggregate and this then is mixed with water to facilitate the properplacing and to pre vent the mix from packing before it is ready forspreading. A typical mix would be as follows:

Bentonite 50 lbs. Asphaltic cement 100 lbs. Portland cement 50 lbs.Mineral aggregate 800 lbs. Water 100 gallons (5) Compositions also maybe used for the integral waterproofing of all types of concrete and forgiving plasticity to concrete mixes, and for preserving steel againstcorrosion which the concrete may be used to incase. For all of thevarieties of purposes for which this composition may be used, it isimportant to very intimately incorporate all the materials. In somecases, it would be necessary to heat the mineral materials so that thebituminous material may be added. When, however, the bituminous or oilymaterial is not semi-solid, solid or highly viscous, the mixing may bedone cold.

(6) Various compositions of bentonite, magnesium oxide, Portland cementand heavy powders such as barytes, galena, sphalerite, pyrite, ironfilings or scale are used in connection with the drilling of oil wells.Some of the important features include:

a. Increasing the head of liquid in the well to hold back gas or softwater.

b. Forming a smooth, strong wall in the open hole of the well.

0. Prevention of caving of the walls of the well.

d. Lubrication of the slush pump and tools.

e. Removing cuttings from the bit face and from the hole.

(7) Bentonite treated in the manner set forth in this application is aparticularly good flocculating agent for use in water filtration. Inmany cases it takes the place of alum and lime, carrying down with itany suspended matter. It is also useful in making a good filter bed onfilter sands and other types of filtering materials. In some cases it isvery desirable for use in filter presses.

(8) Treated bentonite is very much superior to straight bentonite forthe deinking of newspapers. In some instances it is desirable to add theuntreated bentonite to the beater or other vessel in which the newspaperis being deinked and then to add the improver such as magnesium oxide.

(9) Treated bentonite is valuable as a bonding agent for foundry sand,in which case it is used in connection with clay, giving a very superiorwet bond for the sand grains. It is also valuable as a core wash forsuspending graphite or other facing material. Its use results in verymuch smoother castings.

(10) Treated bentonite is particularly useful as a sizing vehicle in themanufacture of paper. It prevents excessive amounts of clay or barytesor other mineral that may be used from pass ing through the screens,holding it in the pulp. For this use the bentonite treated withmagnesium oxide is particularly desirable.

(11) In the manufacture of brick and tile, modified bentonite is veryuseful as a dispersing agent and for giving plasticity with a very largeamount of water. This makes it possible to produce a very light weightproduct, and this product may be subsequently burned to give the properstrength and waterproofness.

(l2) Modified bentonite is a valuable bonding agent in the manufactureof refractory cement and all types of refractories. It is useful in themanufacture of fire clay and graphite crucibles, muflies, melting potsand the like. The magnesium oxide treatment is particularly desirablefor refractory and ceramic materials.

(13) Treated bentonite for use as soap filler and as a detergent agentis preferably made by using a material that does not readily react uponfatty acids, in which case it is a great improvement over straightbentonite.

(14) Modified bentonite, particularly with the magnesium oxidetreatment, is very useful as a lubricant. It is an anticorrosive, and onaccount of the possibility of using it with large percentages of waterit is very valuable in thread cutting. It is used extensively also ingrease compositions.

(15) Bentonite and magnesium oxide, on account of the extreme finenessof grain, is very valuable as a filler in paints. It is particularlyvaluable in calcimines such as in connection with the use of whitePortland cement or other white pigment, as its suspending properties arevery greatly increased over those of straight bentonite and itsconsistencyis more appropriate.

(16) Treated bentonite is particularly useful in the dehydration,bleaching and desulphurizing of oils. The use of magnesium oxide orother oxide is particularly valuable in the removal of certain types ofsulphur compounds.

(17) In the softening of water, bentonite is of particular value whentreated with magnesium oxide or with alkalies. nection with truezeolites, as it greatly extends the reacting value of the zeolite. Whenimproved with Portland cement, the physical properties of the zeoliteare improved. In this case, however, the effect of the Portland cementmust be graduallyovercome, ordinarily by the use of carbon dioxide.

(18) Treated bentonite is particularly useful as an insecticidal base,since it holds the insecticide, fungicide or germicide in a moistcondition and in a dispersed condition for a long period of time.

(19) Other uses include the manufacture of putties, plastics andpharmaceuticals.

I claim as my invention:

1. A composition of matter comprising bentonite and magnesium oxideadded thereto, the latter constituent being present in an amount of tenper cent or less.

2. A composition of matter comprising bentonite and dolomite the latterhaving been burned before mixing at a temperature above 350 C. and below825 C., the dolomite being present in a minor proportion.

3. A composition of matter comprising bentonite and calcined dolomite,the latter constituent ranging from five-tenths per cent to ten per centof the bentonite.

4. A composition of matter capable of forming a gel with ten times itsweight of water and comprising bentonite and magnesium oxide themagnesium oxide being present in an amount of ten per cent or less ofthe bentonite.

5. A composition of matter comprising an intimate mixture of bentoniteand magnesium oxide, the latter being present to the extent of aboutfive per cent of the mass.

6. A composition of matter comprising an intimate mixture of bentoniteand magnesium oxide, the latter being present to the extent of less thanfive per cent of the mass.

'7. A composition of matter including in combination bentonite and afree magnesium oxidebearing magnesite, the free magnesium oxide contentbeing less than 10% of the mass.

ROY CROSS.

It may be used in con-

